HW_1

Author

Tyler Gallagher

Section 1

library(data.table)
library(tidyverse)
── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
✔ dplyr     1.1.2     ✔ readr     2.1.4
✔ forcats   1.0.0     ✔ stringr   1.5.0
✔ ggplot2   3.4.3     ✔ tibble    3.2.1
✔ lubridate 1.9.2     ✔ tidyr     1.3.0
✔ purrr     1.0.2     
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::between()     masks data.table::between()
✖ dplyr::filter()      masks stats::filter()
✖ dplyr::first()       masks data.table::first()
✖ lubridate::hour()    masks data.table::hour()
✖ lubridate::isoweek() masks data.table::isoweek()
✖ dplyr::lag()         masks stats::lag()
✖ dplyr::last()        masks data.table::last()
✖ lubridate::mday()    masks data.table::mday()
✖ lubridate::minute()  masks data.table::minute()
✖ lubridate::month()   masks data.table::month()
✖ lubridate::quarter() masks data.table::quarter()
✖ lubridate::second()  masks data.table::second()
✖ purrr::transpose()   masks data.table::transpose()
✖ lubridate::wday()    masks data.table::wday()
✖ lubridate::week()    masks data.table::week()
✖ lubridate::yday()    masks data.table::yday()
✖ lubridate::year()    masks data.table::year()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors
epa22 <- fread("/Users/TylerGallagher13/Desktop/2022_EPA_Data.csv")
epa02 <- fread("/Users/TylerGallagher13/Desktop/2002_EPA_Data.csv")
dim(epa22)
[1] 57775    20
str(epa22)
Classes 'data.table' and 'data.frame':  57775 obs. of  20 variables:
 $ Date                          : chr  "01/01/2022" "01/02/2022" "01/03/2022" "01/04/2022" ...
 $ Source                        : chr  "AQS" "AQS" "AQS" "AQS" ...
 $ Site ID                       : int  60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 ...
 $ POC                           : int  3 3 3 3 3 3 3 3 3 3 ...
 $ Daily Mean PM2.5 Concentration: num  12.7 13.9 7.1 3.7 4.2 3.8 2.3 6.9 13.6 11.2 ...
 $ UNITS                         : chr  "ug/m3 LC" "ug/m3 LC" "ug/m3 LC" "ug/m3 LC" ...
 $ DAILY_AQI_VALUE               : int  52 55 30 15 18 16 10 29 54 47 ...
 $ Site Name                     : chr  "Livermore" "Livermore" "Livermore" "Livermore" ...
 $ DAILY_OBS_COUNT               : int  1 1 1 1 1 1 1 1 1 1 ...
 $ PERCENT_COMPLETE              : num  100 100 100 100 100 100 100 100 100 100 ...
 $ AQS_PARAMETER_CODE            : int  88101 88101 88101 88101 88101 88101 88101 88101 88101 88101 ...
 $ AQS_PARAMETER_DESC            : chr  "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" ...
 $ CBSA_CODE                     : int  41860 41860 41860 41860 41860 41860 41860 41860 41860 41860 ...
 $ CBSA_NAME                     : chr  "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" ...
 $ STATE_CODE                    : int  6 6 6 6 6 6 6 6 6 6 ...
 $ STATE                         : chr  "California" "California" "California" "California" ...
 $ COUNTY_CODE                   : int  1 1 1 1 1 1 1 1 1 1 ...
 $ COUNTY                        : chr  "Alameda" "Alameda" "Alameda" "Alameda" ...
 $ SITE_LATITUDE                 : num  37.7 37.7 37.7 37.7 37.7 ...
 $ SITE_LONGITUDE                : num  -122 -122 -122 -122 -122 ...
 - attr(*, ".internal.selfref")=<externalptr> 
head(epa22)
         Date Source  Site ID POC Daily Mean PM2.5 Concentration    UNITS
1: 01/01/2022    AQS 60010007   3                           12.7 ug/m3 LC
2: 01/02/2022    AQS 60010007   3                           13.9 ug/m3 LC
3: 01/03/2022    AQS 60010007   3                            7.1 ug/m3 LC
4: 01/04/2022    AQS 60010007   3                            3.7 ug/m3 LC
5: 01/05/2022    AQS 60010007   3                            4.2 ug/m3 LC
6: 01/06/2022    AQS 60010007   3                            3.8 ug/m3 LC
   DAILY_AQI_VALUE Site Name DAILY_OBS_COUNT PERCENT_COMPLETE
1:              52 Livermore               1              100
2:              55 Livermore               1              100
3:              30 Livermore               1              100
4:              15 Livermore               1              100
5:              18 Livermore               1              100
6:              16 Livermore               1              100
   AQS_PARAMETER_CODE       AQS_PARAMETER_DESC CBSA_CODE
1:              88101 PM2.5 - Local Conditions     41860
2:              88101 PM2.5 - Local Conditions     41860
3:              88101 PM2.5 - Local Conditions     41860
4:              88101 PM2.5 - Local Conditions     41860
5:              88101 PM2.5 - Local Conditions     41860
6:              88101 PM2.5 - Local Conditions     41860
                           CBSA_NAME STATE_CODE      STATE COUNTY_CODE  COUNTY
1: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
2: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
3: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
4: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
5: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
6: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
   SITE_LATITUDE SITE_LONGITUDE
1:      37.68753      -121.7842
2:      37.68753      -121.7842
3:      37.68753      -121.7842
4:      37.68753      -121.7842
5:      37.68753      -121.7842
6:      37.68753      -121.7842
tail(epa22)
         Date Source  Site ID POC Daily Mean PM2.5 Concentration    UNITS
1: 12/01/2022    AQS 61131003   1                            3.4 ug/m3 LC
2: 12/07/2022    AQS 61131003   1                            3.8 ug/m3 LC
3: 12/13/2022    AQS 61131003   1                            6.0 ug/m3 LC
4: 12/19/2022    AQS 61131003   1                           34.8 ug/m3 LC
5: 12/25/2022    AQS 61131003   1                           23.2 ug/m3 LC
6: 12/31/2022    AQS 61131003   1                            1.0 ug/m3 LC
   DAILY_AQI_VALUE            Site Name DAILY_OBS_COUNT PERCENT_COMPLETE
1:              14 Woodland-Gibson Road               1              100
2:              16 Woodland-Gibson Road               1              100
3:              25 Woodland-Gibson Road               1              100
4:              99 Woodland-Gibson Road               1              100
5:              74 Woodland-Gibson Road               1              100
6:               4 Woodland-Gibson Road               1              100
   AQS_PARAMETER_CODE       AQS_PARAMETER_DESC CBSA_CODE
1:              88101 PM2.5 - Local Conditions     40900
2:              88101 PM2.5 - Local Conditions     40900
3:              88101 PM2.5 - Local Conditions     40900
4:              88101 PM2.5 - Local Conditions     40900
5:              88101 PM2.5 - Local Conditions     40900
6:              88101 PM2.5 - Local Conditions     40900
                                 CBSA_NAME STATE_CODE      STATE COUNTY_CODE
1: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
2: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
3: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
4: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
5: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
6: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
   COUNTY SITE_LATITUDE SITE_LONGITUDE
1:   Yolo      38.66121      -121.7327
2:   Yolo      38.66121      -121.7327
3:   Yolo      38.66121      -121.7327
4:   Yolo      38.66121      -121.7327
5:   Yolo      38.66121      -121.7327
6:   Yolo      38.66121      -121.7327
summary(epa22$`Daily Mean PM2.5 Concentration`)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
 -2.200   4.200   7.000   8.574  10.900 302.500

A concentration below 0 does not seem possible. I will delete observations below 0 concentration.

epa22 <- epa22[epa22$`Daily Mean PM2.5 Concentration`>0]
summary(epa22$`Daily Mean PM2.5 Concentration`)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
  0.100   4.200   7.000   8.626  10.900 302.500

Now, I will repeat these things for the other data table.

dim(epa02)
[1] 15976    20
str(epa02)
Classes 'data.table' and 'data.frame':  15976 obs. of  20 variables:
 $ Date                          : chr  "01/05/2002" "01/06/2002" "01/08/2002" "01/11/2002" ...
 $ Source                        : chr  "AQS" "AQS" "AQS" "AQS" ...
 $ Site ID                       : int  60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 60010007 ...
 $ POC                           : int  1 1 1 1 1 1 1 1 1 1 ...
 $ Daily Mean PM2.5 Concentration: num  25.1 31.6 21.4 25.9 34.5 41 29.3 15 18.8 37.9 ...
 $ UNITS                         : chr  "ug/m3 LC" "ug/m3 LC" "ug/m3 LC" "ug/m3 LC" ...
 $ DAILY_AQI_VALUE               : int  78 92 71 80 98 115 87 57 65 107 ...
 $ Site Name                     : chr  "Livermore" "Livermore" "Livermore" "Livermore" ...
 $ DAILY_OBS_COUNT               : int  1 1 1 1 1 1 1 1 1 1 ...
 $ PERCENT_COMPLETE              : num  100 100 100 100 100 100 100 100 100 100 ...
 $ AQS_PARAMETER_CODE            : int  88101 88101 88101 88101 88101 88101 88101 88101 88101 88101 ...
 $ AQS_PARAMETER_DESC            : chr  "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" "PM2.5 - Local Conditions" ...
 $ CBSA_CODE                     : int  41860 41860 41860 41860 41860 41860 41860 41860 41860 41860 ...
 $ CBSA_NAME                     : chr  "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" "San Francisco-Oakland-Hayward, CA" ...
 $ STATE_CODE                    : int  6 6 6 6 6 6 6 6 6 6 ...
 $ STATE                         : chr  "California" "California" "California" "California" ...
 $ COUNTY_CODE                   : int  1 1 1 1 1 1 1 1 1 1 ...
 $ COUNTY                        : chr  "Alameda" "Alameda" "Alameda" "Alameda" ...
 $ SITE_LATITUDE                 : num  37.7 37.7 37.7 37.7 37.7 ...
 $ SITE_LONGITUDE                : num  -122 -122 -122 -122 -122 ...
 - attr(*, ".internal.selfref")=<externalptr> 
head(epa02)
         Date Source  Site ID POC Daily Mean PM2.5 Concentration    UNITS
1: 01/05/2002    AQS 60010007   1                           25.1 ug/m3 LC
2: 01/06/2002    AQS 60010007   1                           31.6 ug/m3 LC
3: 01/08/2002    AQS 60010007   1                           21.4 ug/m3 LC
4: 01/11/2002    AQS 60010007   1                           25.9 ug/m3 LC
5: 01/14/2002    AQS 60010007   1                           34.5 ug/m3 LC
6: 01/17/2002    AQS 60010007   1                           41.0 ug/m3 LC
   DAILY_AQI_VALUE Site Name DAILY_OBS_COUNT PERCENT_COMPLETE
1:              78 Livermore               1              100
2:              92 Livermore               1              100
3:              71 Livermore               1              100
4:              80 Livermore               1              100
5:              98 Livermore               1              100
6:             115 Livermore               1              100
   AQS_PARAMETER_CODE       AQS_PARAMETER_DESC CBSA_CODE
1:              88101 PM2.5 - Local Conditions     41860
2:              88101 PM2.5 - Local Conditions     41860
3:              88101 PM2.5 - Local Conditions     41860
4:              88101 PM2.5 - Local Conditions     41860
5:              88101 PM2.5 - Local Conditions     41860
6:              88101 PM2.5 - Local Conditions     41860
                           CBSA_NAME STATE_CODE      STATE COUNTY_CODE  COUNTY
1: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
2: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
3: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
4: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
5: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
6: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
   SITE_LATITUDE SITE_LONGITUDE
1:      37.68753      -121.7842
2:      37.68753      -121.7842
3:      37.68753      -121.7842
4:      37.68753      -121.7842
5:      37.68753      -121.7842
6:      37.68753      -121.7842
tail(epa02)
         Date Source  Site ID POC Daily Mean PM2.5 Concentration    UNITS
1: 12/10/2002    AQS 61131003   1                             15 ug/m3 LC
2: 12/13/2002    AQS 61131003   1                             15 ug/m3 LC
3: 12/22/2002    AQS 61131003   1                              1 ug/m3 LC
4: 12/25/2002    AQS 61131003   1                             23 ug/m3 LC
5: 12/28/2002    AQS 61131003   1                              5 ug/m3 LC
6: 12/31/2002    AQS 61131003   1                              6 ug/m3 LC
   DAILY_AQI_VALUE            Site Name DAILY_OBS_COUNT PERCENT_COMPLETE
1:              57 Woodland-Gibson Road               1              100
2:              57 Woodland-Gibson Road               1              100
3:               4 Woodland-Gibson Road               1              100
4:              74 Woodland-Gibson Road               1              100
5:              21 Woodland-Gibson Road               1              100
6:              25 Woodland-Gibson Road               1              100
   AQS_PARAMETER_CODE       AQS_PARAMETER_DESC CBSA_CODE
1:              88101 PM2.5 - Local Conditions     40900
2:              88101 PM2.5 - Local Conditions     40900
3:              88101 PM2.5 - Local Conditions     40900
4:              88101 PM2.5 - Local Conditions     40900
5:              88101 PM2.5 - Local Conditions     40900
6:              88101 PM2.5 - Local Conditions     40900
                                 CBSA_NAME STATE_CODE      STATE COUNTY_CODE
1: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
2: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
3: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
4: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
5: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
6: Sacramento--Roseville--Arden-Arcade, CA          6 California         113
   COUNTY SITE_LATITUDE SITE_LONGITUDE
1:   Yolo      38.66121      -121.7327
2:   Yolo      38.66121      -121.7327
3:   Yolo      38.66121      -121.7327
4:   Yolo      38.66121      -121.7327
5:   Yolo      38.66121      -121.7327
6:   Yolo      38.66121      -121.7327
summary(epa02$`Daily Mean PM2.5 Concentration`)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.00    7.00   12.00   16.12   20.50  104.30

Since the minimum concentration is zero, this is a logical reading. We can move on to next steps.

Section 2

library(dplyr)
epa22 <- epa22 %>%
  mutate(year = "2022")
epa02 <- epa02 %>%
  mutate(year = "2002")
epa0222 <- rbind(epa02, epa22)
head(epa0222)
         Date Source  Site ID POC Daily Mean PM2.5 Concentration    UNITS
1: 01/05/2002    AQS 60010007   1                           25.1 ug/m3 LC
2: 01/06/2002    AQS 60010007   1                           31.6 ug/m3 LC
3: 01/08/2002    AQS 60010007   1                           21.4 ug/m3 LC
4: 01/11/2002    AQS 60010007   1                           25.9 ug/m3 LC
5: 01/14/2002    AQS 60010007   1                           34.5 ug/m3 LC
6: 01/17/2002    AQS 60010007   1                           41.0 ug/m3 LC
   DAILY_AQI_VALUE Site Name DAILY_OBS_COUNT PERCENT_COMPLETE
1:              78 Livermore               1              100
2:              92 Livermore               1              100
3:              71 Livermore               1              100
4:              80 Livermore               1              100
5:              98 Livermore               1              100
6:             115 Livermore               1              100
   AQS_PARAMETER_CODE       AQS_PARAMETER_DESC CBSA_CODE
1:              88101 PM2.5 - Local Conditions     41860
2:              88101 PM2.5 - Local Conditions     41860
3:              88101 PM2.5 - Local Conditions     41860
4:              88101 PM2.5 - Local Conditions     41860
5:              88101 PM2.5 - Local Conditions     41860
6:              88101 PM2.5 - Local Conditions     41860
                           CBSA_NAME STATE_CODE      STATE COUNTY_CODE  COUNTY
1: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
2: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
3: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
4: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
5: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
6: San Francisco-Oakland-Hayward, CA          6 California           1 Alameda
   SITE_LATITUDE SITE_LONGITUDE year
1:      37.68753      -121.7842 2002
2:      37.68753      -121.7842 2002
3:      37.68753      -121.7842 2002
4:      37.68753      -121.7842 2002
5:      37.68753      -121.7842 2002
6:      37.68753      -121.7842 2002
summary(epa0222$year)
   Length     Class      Mode 
    73416 character character 
names(epa0222)[names(epa0222) == "Daily Mean PM2.5 Concentration"] <- "PM2.5"
summary(epa0222$PM2.5)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.00    4.60    7.70   10.26   12.50  302.50

Section 3

library(leaflet)
library(RColorBrewer)
my_map <- leaflet(data = epa0222) %>%
  addTiles()
color_mapping <- colorFactor(
  palette = "Set1",
  domain = epa0222$year
)
my_map <- my_map %>%
  addCircleMarkers(
    lng = ~SITE_LONGITUDE,
    lat = ~SITE_LATITUDE, 
    color = ~color_mapping(year),
    radius = 5,
    fillOpacity = 0.7 
  )
my_map

There are monitoring sites throughout California. There is a region in the Southeast of the state that is poorly covered by weather monitoring devices. There is a heavy concentration along the coastline, particularly in Los Angeles and San Francisco.

Section 4

In section 1, I already addressed the issue of implausible values for PM2.5 concentration (ones that were negative).

summary(epa0222$PM2.5)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.00    4.60    7.70   10.26   12.50  302.50

There do not appear to be any missing NA values.

Section 5

First, we will create summary statistics and exploratory plots for the state level.

table(epa0222$STATE)

California 
     73416 
summary(epa0222$PM2.5)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.00    4.60    7.70   10.26   12.50  302.50 
hist(epa0222$PM2.5)

boxplot(epa0222$PM2.5, col = "magenta")

plot(epa0222$year, epa0222$PM2.5, pch=10, cex=0.5)

It appears that in California generally, the data is right-skewed, meaning most days have a lower mean PM2.5 level, but there are many outliers at higher levels. There is a daily mean of 10.2, though highest readings are above 300. This trend is particularly accentuated in the boxplot. The scatterplot shows that there are many higher individual mean days in 2022 as opposed to 2002.

Now, we will create summary statistics and exploratory plots for the county level.

table(epa0222$COUNTY)

        Alameda           Butte       Calaveras          Colusa    Contra Costa 
           1989            1580             414             496            1097 
      Del Norte       El Dorado          Fresno           Glenn        Humboldt 
            562             436            3533             328             175 
       Imperial            Inyo            Kern           Kings            Lake 
           1743            2157            4113             804             122 
    Los Angeles          Madera           Marin        Mariposa       Mendocino 
           7003             360             573             868             821 
         Merced           Modoc            Mono        Monterey          Nevada 
            808               2             805            1221            1232 
         Orange          Placer          Plumas       Riverside      Sacramento 
           1350            1837            1451            5192            3360 
     San Benito  San Bernardino       San Diego   San Francisco     San Joaquin 
            594            3730            4476             546            1158 
San Luis Obispo       San Mateo   Santa Barbara     Santa Clara      Santa Cruz 
           1598             449            1672            1651             752 
         Shasta        Siskiyou          Solano          Sonoma      Stanislaus 
            752             805             816             439             954 
         Sutter          Tehama         Trinity          Tulare         Ventura 
            829             347             489            1719            2691 
           Yolo 
            517 
lac_data <- subset(epa0222, COUNTY == "Los Angeles")
summary(lac_data$PM2.5)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.20    7.90   11.50   13.37   16.10   72.40 
hist(lac_data$PM2.5)

boxplot(lac_data$PM2.5, col = "pink")

plot(lac_data$year, lac_data$PM2.5, pch=10, cex=0.5)

It appears that in Los Angeles county generally, the data is right-skewed, meaning most days have a lower mean PM2.5 level, but there are many outliers at higher levels. Mean PM2.5 level is 13.2 with highest numbers above 70. This trend is particularly accentuated in the boxplot. The scatterplot shows that the highest mean days of PM2.5 are in 2002 as opposed to 2020, which is different from the trends at the overall California level.

Now, we will create summary statistics and plots for the site in Los Angeles.

table(epa0222$'Site Name')

                                                  
                                              823 
                                         29 Palms 
                                              414 
                          3425 N FIRST ST, FRESNO 
                                              499 
                                           Alpine 
                                              379 
                               Alturas-Fourth St. 
                                                2 
                                          Anaheim 
                                             1123 
                            Aqua Tibia Wilderness 
                                              168 
                                Arroyo Grande CDF 
                                              359 
                                       Atascadero 
                                              350 
                       Atascadero (original site) 
                                              116 
                                    Auburn-Atwood 
                                              350 
                                            Azusa 
                                              415 
                      Bakersfield-Airport (Planz) 
                                              231 
                           Bakersfield-California 
                                             2008 
                        Bakersfield-Golden / M St 
                                              421 
                                  Banning Airport 
                                              365 
                                         Big Bear 
                                              450 
                                 Bishop Tribe EMO 
                                              354 
                                         Bliss SP 
                                              113 
                          Brawley-220 Main Street 
                                              358 
                             Brawley-401 Main St. 
                                               85 
                                          Burbank 
                                              122 
                            Calexico-Ethel Street 
                                              613 
                                   Camp Pendleton 
                                              357 
                         Campo Indian Reservation 
                                              362 
                                    Carmel Valley 
                                              343 
                            Chester-222 First Ave 
                                              289 
                                Chico-East Avenue 
                                              410 
                             Chico-Manzanita Ave. 
                                              120 
                                      Chula Vista 
                                              218 
                                     Clovis-Villa 
                                              443 
                                 Colfax-City Hall 
                                              358 
                              Colusa-Sunrise Blvd 
                                              454 
                                          Compton 
                                              723 
                                          Concord 
                                              739 
                               Corcoran-Patterson 
                                              443 
                         Cortina Indian Rancheria 
                                               42 
                Crescent City-Crescent Elk School 
                                              332 
                                        Crestline 
                                              178 
                                 Davis-UCD Campus 
                                              346 
                   Death Valley NP - Park Village 
                                              115 
                                          Donovan 
                                              360 
                                      Echo Summit 
                                                2 
                                         El Cajon 
                                              416 
           El Cajon - Lexington Elementary School 
                                              491 
                             El Centro-9th Street 
                                              452 
                        El Rio-Rio Mesa School #2 
                                              469 
                                        Escondido 
                                              355 
                                  Eureka I Street 
                                               59 
                                Folsom-Natoma St. 
                                              689 
                                          Fontana 
                                              298 
                             Fremont - Chapel Way 
                                              105 
                                 Fresno - Garland 
                                              542 
                                   Fresno-Foundry 
                                              363 
                                   Fresno-Pacific 
                                              443 
                                           Gilroy 
                                              349 
                                         Glendora 
                                              361 
                                           Goleta 
                                              359 
                     Grass Valley-Litton Building 
                                              406 
                                    Hanford-Irwin 
                                              361 
                                        Hollister 
                                              356 
                                Hoover Wilderness 
                                              228 
                                            Huron 
                                              360 
                                            Indio 
                                              240 
                                           Jacobs 
                                              116 
                      Joshua Tree NP - Black Rock 
                                              215 
                                Kaiser Wilderness 
                                              195 
                                      Kearny Mesa 
                                              111 
                                           Keeler 
                                              641 
                                      King City 2 
                                              348 
                                    Lake Elsinore 
                                              360 
                     Lake Tahoe Community College 
                                              111 
                          Lakeport-Lakeport Blvd. 
                                               61 
                          Lakeport-S. Main Street 
                                               61 
                        Lancaster-Division Street 
                                              458 
                                    Laney College 
                                              360 
 Lassen Volcanic NP - Manzanita Lake Fire Station 
                                              210 
                      Lava Beds National Monument 
                                              216 
                                            Lebec 
                                              489 
                          Lebec-Peace Valley Road 
                                               93 
            Lebec-Peace Valley/Frazier Park Roads 
                                              106 
                                       Lee Vining 
                                              363 
                          Lincoln-2885 Moore Road 
                                              357 
                                        Livermore 
                                              439 
                                  Lompoc H Street 
                                              358 
            Lone Pine Paiute-Shoshone Reservation 
                                              302 
                               Long Beach (North) 
                                              411 
                               Long Beach (South) 
                                              243 
                   Long Beach-Route 710 Near Road 
                                              625 
                    Los Angeles-North Main Street 
                                             1276 
                                          Lynwood 
                                              122 
                                      Madera-City 
                                              360 
                                          Mammoth 
                                              214 
                                          Manteca 
                                              340 
                                    Merced-Coffee 
                                              359 
                                      Merced-M St 
                                              449 
                                            Mesa2 
                                              358 
                            Mira Loma (Van Buren) 
                                              778 
                                    Mission Viejo 
                                              227 
                              Modesto-14th Street 
                                              598 
                                           Mojave 
                                              100 
                          Mojave - CA 58 Business 
                                              355 
                   Morongo Air Monitoring Station 
                                              370 
                           North Hollywood (NOHO) 
                                              365 
                                          Oakland 
                                              365 
                                     Oakland West 
                                              359 
                             Ojai - East Ojai Ave 
                                              360 
                             Ontario Fire Station 
                                              111 
                       Ontario-Route 60 Near Road 
                                              705 
                                      Pala Airpad 
                                              347 
                                     Palm Springs 
                                              239 
                               Paradise - Theater 
                                              350 
                                         Pasadena 
                                              241 
                                         Pechanga 
                                              401 
                                   Pico Rivera #2 
                                              118 
Pinnacles NP - Southwest of East Entrance Station 
                                              238 
                                   Piru - Pacific 
                                              475 
                            Pleasanton - Owens Ct 
                                              361 
                    Point Reyes NS Ranger Station 
                                              213 
                                      Porterville 
                                              356 
                                          Portola 
                                              552 
                        Portola-161 Nevada Street 
                                              100 
                           Quincy-N Church Street 
                                              510 
             Red Bluff-Walnut St. District Office 
                                              347 
                                Redding - Buckeye 
                                               54 
                      Redding - Health Department 
                                              429 
                                  Redding - Toyon 
                                               59 
                                     Redwood City 
                                              449 
                                       Redwood NP 
                                              230 
                                           Reseda 
                                              602 
                        Ridgecrest-California Ave 
                                              104 
                                  Ridgecrest-Ward 
                                              355 
                             Riverside (Magnolia) 
                                              115 
                          Roseville-N Sunrise Ave 
                                              417 
                                         Rubidoux 
                                             1377 
      Sacramento Health Department-Stockton Blvd. 
                                              154 
                         Sacramento-1309 T Street 
                                              826 
                          Sacramento-Bercut Drive 
                                              359 
                        Sacramento-Del Paso Manor 
                                              988 
                                        Salinas 3 
                                              530 
                     San Andreas-Gold Strike Road 
                                              414 
                                   San Bernardino 
                                              235 
                     San Diego - Kearny Villa Rd. 
                                              172 
            San Diego - Sherman Elementary School 
                                              437 
                   San Diego -Rancho Carmel Drive 
                                              119 
                               San Diego-12th Ave 
                                              352 
                                    San Francisco 
                                              546 
                                         San Jose 
                                              217 
                               San Jose - 4th St. 
                                              141 
                               San Jose - Jackson 
                                              586 
                           San Jose - Knox Avenue 
                                              358 
                 San Lorenzo Valley Middle School 
                                              345 
                        San Luis Obispo-Marsh St. 
                                               52 
                                        San Pablo 
                                              358 
                                       San Rafael 
                                              360 
                            San Rafael Wilderness 
                                              187 
                                    Santa Barbara 
                                              349 
                                    Santa Clarita 
                                              365 
                                       Santa Cruz 
                                              407 
                                      Santa Maria 
                                               60 
                              Santa Rosa - 5th St 
                                               93 
                                       Sebastopol 
                                              346 
        Sequoia & Kings Canyon NPs - Ash Mountain 
                                              340 
                          Sequoia NP-Ash Mountain 
                                              226 
                               Signal Hill (LBSH) 
                                              289 
                       Simi Valley-Cochran Street 
                                              873 
                                      SLO Roberto 
                                              363 
                                      Sloughhouse 
                                              344 
                       South Lake Tahoe-Sandy Way 
                                               93 
                       Stn.1 Big Pine Paiute site 
                                              325 
                       Stockton - University Park 
                                              349 
                                Stockton-Hazelton 
                                              124 
               Table Mountain Air Monitoring Site 
                                              339 
                         Tahoe City-Fairway Drive 
                                              355 
                                         Temecula 
                                              365 
                                    Thousand Oaks 
                                              514 
                      Torres Martinez Reservation 
                                              235 
                                    Tracy-Airport 
                                              345 
                        TRAFFIC, RURAL PAVED ROAD 
                                              700 
                                     Tranquillity 
                                              349 
                                          Trinity 
                                              139 
                             Truckee-Fire Station 
                                              826 
                                          Turlock 
                                              356 
                                    Ukiah-Library 
                                              470 
                                           Upland 
                                              365 
                                          Vallejo 
                                              816 
                          Victorville-Park Avenue 
                                              944 
                                   Visalia-Church 
                                              404 
                        Visalia-W. Ashland Avenue 
                                              393 
                           Weaverville-Courthouse 
                                              350 
White Mountain Research Center - Owens Valley Lab 
                                              420 
                             Willits-Blosser Lane 
                                              351 
                            Willows-Colusa Street 
                                              328 
                             Woodland-Gibson Road 
                                              171 
                    Yosemite NP - Turtleback Dome 
                                              340 
       Yosemite NP-Yosemite Village Vistor Center 
                                              528 
                                            Yreka 
                                              589 
                                        Yuba City 
                                              829 
los_angeles_data <- subset(epa0222, `Site Name` == "Los Angeles-North Main Street")
summary(los_angeles_data$PM2.5)
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   2.40    8.90   12.40   14.56   17.20   66.30 
boxplot(los_angeles_data$PM2.5, col = "orange")

hist(los_angeles_data$PM2.5)

plot(los_angeles_data$year, los_angeles_data$PM2.5, pch=10, cex=0.5)

It appears that in Los Angeles city, the data is right-skewed, meaning most days have a lower mean PM2.5 level, but there are many outliers at higher levels. Mean PM2.5 level is 14.6 with highest numbers above 60. This trend is particularly accentuated in the boxplot. The scatterplot shows that the highest mean days of PM2.5 are in 2002 as opposed to 2020, which is different from the trends at the overall California level.